Rail braces are utilized to buttress railroad switch stock rails against the side thrusts of the rail traffic tending to overturn them. When a rail is overturned, the head of the rail is rotated about the origin of the rail to a position in which it is angularly offset with respect to a vertical line through the vertical axis of the rail. The head of the rail rotates with respect to the base of the rail because the base is anchored or fixed in the rail ties whereas the head of the rail which supports the traffic load is free to move. Rotation of the rail head is undesirable because if a lateral load is applied to the head of a rail over a relatively long length of rail, it is possible that the lateral load may cause the entire rail to roll over.
A rail brace supports a stock rail by being restrained against movement towards the rail and by having an upper surface which bears against a fishing surface formed on the underside of the head of the rail and a lower surface which bears against a fishing surface formed on the top side of the base of the rail. Traditionally, some braces have been anchored by being spiked to a wooden tie. However, rail braces eventually loosen and it is necessary to periodically tighten the brace so that it firmly engages the base and head of the rail. When a brace is spiked to a tie, it is necessary to remove the spikes and redrive them. Eventually the tie must be replaced because it has an excessive number of spike holes.
Because of the disadvantages inherent in fixed rail braces, adjustable braces were developed which eliminated the need to respike the brace assembly each time the brace was tightened. In one type of adjustable brace, one side of the base of the brace is set at an angle and this side directly engages a stop on the tie plate set at a similar angle to thereby provide a wedging action of the brace between the rail and the stop. In another type of adjustable brace, a wedge is interposed between the brace and a stop secured to the tie plate. After the wedge or brace is driven into position, the adjustable brace may be secured by bolts, nuts or by lag screws. In some instances, the wedge member has been secured by having a cover plate that is secured by bolts to the tie plate to engage the wedge member or the wedge member and the brace to thereby secure these elements.
Because it is has been found inconvenient to utilize bolts or lag screws to secure rail braces, the railroad industry recently has begun to utilize elastic fasteners such as spring clips to bias adjustable rail braces against stock rails. In one type of adjustable brace utilizing a spring clip, the base of the brace is set at an angle with respect to the surfaces on the brace which engage the rail and the angled base engages a stop mounted on the tie plate set at a similar angle to thereby provide a wedging action for urging the brace against the rail. The elastic fastener biases a cover plate downwardly against a flat surface formed on the top of the brace to prevent vertical and horizontal movement of the brace. The surface on the brace may be corrugated and engage a similarly corrugated surface formed on the bottom of the cover plate to further inhibit logitudinal movement of the brace. The axis of the elastic fastener is non-parallel to the surfaces of the rail brace which engage the stock rail. One problem with having the axis of the fastener non parallel to that of the rail is that automatic equipment utilized to install such fasteners can only install these fasteners if the axes of the fasteners is parallel to that of the rail. If the axes are not parallel to the rail, the fasteners must be installed manually.
It has been found that where an elastic fastener has been utilized to clamp or lock a cover plate against a horizontal surface on a rail brace, vibration and movement of the rail may cause the rail brace to loosen. This occurs because as the traffic passes over the rail, the rail and the brace move vertically downwardly and momentarily may be out of contact with the cover plate. As a result, the top surface of the brace tends to separate from the cover plate and the brace and cover plate are no longer locked together. Over a period of time, the rail brace may move horizontally with respect to the cover plate and move away from the rail.
Accordingly, it has been found desirable to provide an adjustable rail brace assembly that is retained in position by an elastic fastener in which the rail brace is permitted to move in a vertical plane with respect to the locking member, but is restrained from moving in a horizontal plane with respect to the locking member.
Additionally, it has been found desirable to provide an adjustable rail brace assembly in which a rail brace, having rail engaging surfaces is retained in position by a cover plate biased into contact therewith by an elastic fastener in which the axis of the fastener is parallel to the rail engaging surfaces of the rail brace.